勾搭hit on someone
hit on someone/flirt with someone/
to make a pass at someone/ to come on to someone
make a pass at someone: 挑逗、示爱
意思是speak to or touch someone in a way that shows you would like to start a sexual relationship with them.
When I found that a stranger began to make a pass at me, I gave him a stern look and left.
to come on to someone?
It's a slang expression that means "to express romantic or sexual interest in someone else."
to have a crush on someone，喜欢某人。
但是，如果你是我的好朋友，不能说I have a crush on you！！！
因为 "to have a crush on someone" means you like that person romantically.